Submission #1092804

#	Time	Username	Problem	Language	Result	Execution time	Memory
1092804		juicy	Palindrome-Free Numbers (BOI13_numbers)	C++17	100 / 100	1 ms	600 KiB

numbers

#include <bits/stdc++.h>

using namespace std;

#ifdef LOCAL
#include "debug.h"
#else
#define debug(...) 42
#endif

long long dp[18][11][11];
string s;

long long rec(int i, int j, int k, bool lower, bool valid) {
  if (i == 18) {
    return valid;
  }
  if (dp[i][j][k] != -1 && lower && valid) {
    return dp[i][j][k];
  }
  int m = lower ? 9 : s[i] - '0';
  long long res = 0;
  for (int c = 0; c <= m; ++c) {
    if (c ^ j && c ^ k) {
      bool lo = lower || c < m, ok = valid || c;
      res += rec(i + 1, ok ? c : 10, j, lo, ok);
    }
  }
  return lower && valid ? dp[i][j][k] = res : res;
}

long long calc(long long x) {
  if (x < 0) {
    return x;
  }
  s = to_string(x);
  while (s.size() < 18) {
    s = '0' + s;
  }
  return rec(0, 10, 10, 0, 0);
}

int main() {
  ios::sync_with_stdio(false); cin.tie(nullptr);

  long long a, b; cin >> a >> b;
  memset(dp, -1, sizeof(dp));
  cout << calc(b) - calc(a - 1);
  return 0;
}

• Subtask 1: 25 / 25
• Subtask 2: 75 / 75